TAS1 experienced sustained negative pricing at –$15.01/MWh across five consecutive intervals (22:00–22:25 on 18 September 2026), before prices sharply recovered to $270.04/MWh in the following interval. The event occurred during high renewable generation, with combined hydro and wind output totalling approximately 1,521 MW across the region.
The negative pricing reflects an oversupply of generation relative to local demand, with high wind and hydro output unable to be fully absorbed within TAS1. A binding constraint (F_T+RREG_0050) carried a substantial marginal value of $282.59, indicating it was restricting the ability to export or redistribute surplus generation, thereby forcing the regional price into negative territory to incentivise load and curtailment. The sharp price recovery in the subsequent interval suggests the constraint condition eased, allowing the market to clear at conventional levels.
Causal analysis generated by gridIQ's synthesis model from live AEMO market data: dispatch prices, generation mix, interconnector flows and market notices in the interval surrounding the event.